Dense wavelength division multiplexing (DWDM) may be used to increase bandwidth in optical communication links. In systems implementing DWDM, multiple optical signals may be combined and transmitted on the same optical fiber simultaneously. Each of the optical signals has different wavelengths. In effect, one fiber is transformed into multiple virtual fibers. Communication networks that implement DWDM networks can carry different types of traffic at different speeds.
An example of a communication network that implements DWDM may be referred to as a metro DWDM communication network. The metro DWDM communication network may be installed to serve cities or metropolitan areas. The metro DWDM communication network may communicate data hundreds of kilometers.
In communication networks implementing DWDM such as the metro DWDM communication network, chromatic dispersion may occur. Chromatic dispersion may result in pulse broadening and an increase in bit errors, for instance. Chromatic dispersion may result from the physical properties of the optical fibers and the optical signals and may act to effectively slow the feasible baud rate of optical signals.
Optical polarization multiplexing can be used to double the data capacity of each wavelength channel or to transmit pilot carrier oscillator signals to aid in detection. In systems implementing optical polarization multiplexing, optical signal state of polarization (SOP) may be rotated by the fiber birefringence, which may require some form of polarization control or demultiplexing at the receiver. Polarization demultiplexing is accomplished using digital signal processing multi-input multi-output (DSP MIMO) processing in digital coherent receivers. One type of receiver that performs the polarization demultiplexing is referred to as digital coherent receivers. The digital coherent receivers use a local oscillator laser, and the DSP MIMO. However, the local oscillator laser increases the cost of the digital coherent receivers and the DSP MIMO processing increases the power dissipation of the transceiver. An efficient scheme for polarization control/demultiplexing in the optical domain may enable single polarization coherent receivers based on pilot carrier with lower cost and lower power use.
The subject matter claimed herein is not limited to embodiments that solve any disadvantages or that operate only in environments such as those described above. Rather, this background is only provided to illustrate one example technology area where some embodiments described herein may be practiced.
all in accordance with at least one embodiment described herein.